Method of forming structures by deposition

ABSTRACT

A method of forming structures by deposition from a pulp, comprising placing drainage means at the base portion of the structure to be formed, the drainage means being associated with means for adjusting the rate of water outflow therefrom, depositing pulp directly on the ground above the drainage means so that water in the pulp outflows through the drainage means while solids in the pulp accumulate above the drainage means and form a deposited structure with upper inclined surfaces. The intensity of the outflow of water from the drainage means is controlled in the course of the depositing operation so as to progressively diminish outflow in the direction from the periphery of the structure being deposited toward the central portion thereof.

United States Patent [191 [111 3,731,492

Ageev et al. 51 May 8, 1973 54] METHOD OF FORMING STRUCTURES 704,181 7 1902 Foote ..6l/30 BY EPOSITION 606,980 7/1898 Poincy ..61/30 Inventors: Georgy Sergeevich Ageev; Ivan Pavlovich Kuptsov; Lev Veniaminovich Jusim, all of Moscow, U.S.S.R.

Assignee: Vsesojuzny Gosudarstvenny ()rdena Lenina Proektny Institute Teploelektroproekt, Moscow, U.S.S.R.

Primary Examiner-Jacob Shapiro Attorney-Waters, Roditi, Schwartz & Nissen 57 ABSTRACT A method of forming structures by deposition from a pulp, comprising placing drainage means at the base portion of the structure to be formed, the drainage means being associated with means for adjusting the rate of water outflow therefrom, depositing pulp directly on the ground above the drainage, means so that water in the pulp outflows through the drainage means while solids in the pulp accumulate above'the drainage means and form a deposited structure with upper inclined surfaces. The intensity of the outflow of water from the drainage means is controlled in the course of the depositing operation so as to progressively diminish outflow in the direction from the periphery of the structure being deposited toward the central portion thereof.

2 Claims, 2 Drawing Figures METHOD OF FORMING STRUCTURES BY DEPOSITION The present invention relates to methods of forming structures, employed in hydraulic engineering, and, more particularly, it relates to methods of forming structures, such as weirs, dams, soil and rock clumps, ash heaps and the like by deposition from pulp such as sand pulp, paper pulp etc.

At present, there is a widely known method of constructing dams, dumps, etc. by deposition from pulp, in accordance with which the pulp is stored so that its solid particles settle in storage ponds located at the area at which the structure is to be formed, when a dam of the so-called deposition or levee chart type is to be constructed.

As the solid particles in the pulp settle, the clarified water is withdrawn from the surface of the storage pond by means of drainage pits.

The main disadvantages of this known method is the necessity of pre-forming levees surrounding the area over which the dam is to be deposited, as well as the necessity of building up these levees and the'drainage pits, as the structure grows.

The above operations involve the use of soil-working machinery and thus increases the construction costs and complicate the construction process.

Another important disadvantage of the method is the comparatively small density of the body of the deposited structure, which is particularly undesirable in cases when this structure is a weir or a dam. Thus, in certain cases it is necessary to perform additional compacting operations on this structures, using vibration, explosion, etc.

Additionally, the abovedescribed method is extremely time-consuming, on account of the slow rate of the pulp settling process, and of the poor water yielding of the matter to be deposited. The last-mentioned circumstance results in a situation in which the supply of the pulp to'the storage pond is periodically interrupted, so as to give this matter enough time to concentrate to an appropriate'level.

Attempts were made to intensify the process of deposition by increasing the supply of the pulp, by eliminating intervals in the pulp supply or-by shortening these intervals; however, such attempts usually led to the formation of quick ground that resulted, as a rule,

in a complete breakdown of the structure.

It can also be considered a disadvantage of the known method that the degree of clarification of withdrawn water is inadequate, which prevents directing this water into water reservoirs without running the risk of polluting the latter.

Consequently, the necessity appears of providing pumping stations either for returning the water for re peated use, even when this is not desirable either technologically or economically, or for directing this water for additional clarification.

It is an object of the present invention to overcome the disadvantages of the known method.

The present invention has for its aim the creation of a method which provides for intensive and controllable de-watering of the pulp.

This aim is attained by a method of forming structures by deposition from pulp, and, in accordance with the present invention, comprises the steps of laying drainage means at the base portion of said structure to be deposited, said drainage means being associated with means for adjusting the rate of water discharge or outflow therefrom, and controlling the intensity of the outflow of water from said drainage means in the course of the depositing operation, in the direction from the periphery of said structure toward the central portion thereof, said pulp, as it is being supplied, being distributed over the front of the formation of the inclines of said structure.

This new method offers active control over the process of deposition and reduces the hydrostatic and filtration pressure upon the side prisms of the structure.

When the water permeability of the material being deposited is insufficient, it is highly advisable to supply the pulp through classifying means so that the solid particles of coarser fractions are distributed adjacent to said inclines of said structure and the solid particles of finer fractions are distributed adjacent to the central portion thereof.

In this way it becomes possible to improve the conditions of filtration of water through the side prisms of the structure and to ensure greater stability of the inclines.

A detailed description of the present invention is given below in connection with a practical embodiment thereof, with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic vertical sectional view of an ash dam in the course of deposition, with illustrated arrangement of the drainage means and pulp conduits, and

FIG. 2 is the schematic plan view of the structure shown in FIG. 1.

The operation of aggrading or depositing a darn, weir, dump etc., begins with placing drainage means 1, 2 and 3, e.g., drainage pipes over the area where th deposition is to take place.

The drainage means can be placed either over the entire area to be occupied by the structure being I deposited, or over only those portions of the area where the inclines of this structure will be.

The drainage means can be arranged either in rows equidistant from the outline of the structure at the base thereof, orelse in parallel rows over the entire area of the base of the structure or in any other appropriate order. 5 i

The outline of the base of the structure being deposited can be of any shape depending solely on the character of the structure and on the relief of the site.

The outlet ends of the drainage means are provided with gates 3a or with any other appropriate means for controlling the outflow of water therethrough. In this way it becomes possible to regulate the process of filtration and the rate of deposition over the corresponding portions of the base of the structure. This regulation of the water outflow should be performed so that at the initial stage of the depositing operation the most intensive outflow of water should be-effected along the outline of the base of the structure, where the inclines of the structure should be initiated. It is here that the relatively dry portions of the inclines will be situated.

The pulp, i.e., the water suspension of the material to be deposited, is supplied through the pulp conduit 4, for distribution over the whole area of the deposition of the incline.

As the pulp flows by gravity from the points of its discharge toward the drainage means, there takes place infiltration of the water contained by the pulp into the incline being formed and filtration of the water into the drainage means, the solid particles of the pulp being deposited on the surface of the wet portion of the inclines, whereby the height of these inclines grows, as the operation of deposition is continued.

The length of the path of the progress of the pulp, over which all the water contained in the pulp is infiltrated, as well as the length of the wet portion of the inclines of the structure being deposited, depend on the value of the specific rate of the discharge of the pulp and on the water permeability of the deposited particles.

Beyond the line where the infiltration of the water is completed, the dry portion of the inclines is formed; the slope angle is approximately equal to the internal friction angle of the solid material contained in the pulp.

By adjusting the rate of the water outflow from the drainage means and by varying the rate of the discharge of the pulp, it becomes possible to obtain practically any length of the wet portion of the inclines, and thus to ensure that the profile of the structure being deposited acquires a desired shape,

Thus, for instance, water may be discharged simultaneously through the assembly of the drainage means located along the incline being formed. In this case the inclines acquire a stepped profile, which in certain cases is desirable, when a waste heap is being formed.

At the initial stage of a depositing operation, it is essential that the water should be discharged most intensively from the group 1 of the drainage means, for the infiltration of the entire amount of water contained in the pulp to be completed above this very group of drainage means, in which manner there is formed a first tier of the structure, with the dry portion of the inclines starting above the drainage means 1.

The above stage completed, the gate through which water from the group 2 of the drainage means is opened, for the infiltration to be completed above this group 2, whereby there is formed the second tier of the structure, with the dry portion of the inclines starting above this group 2; then the same is performed with the group 3 of the drainage means, and so on.

A single drain with adequately developed surface may be used instead of any one of the abovementioned groups of drainage means.

In the central portion of the structure 5, e.g., of an ash heap, there can be maintained a storage pond 6 from which the outflow of water can be effected either through drainage means or from the surface of the pond.

When the water permeability of the soil or ash on which the structure or heap is deposited is inadequate, and also when it is desirable to attain optimal distribution of the material being deposited according to the particle size of the fractions thereof, the particles should be classified by size. In this case the coarsest particles are deposited into the side prisms 7, 8 and 9 of the body being deposited, by the method that has been described hereinabove, while finer particles are directed into the storage pond 6 maintained in the central portion of the structure.

it should be pointed out that the continuous growth of the layer of the deposited particles throughout the deposition thereof positively prevents colmatage, While the continuous wetting of the inclines of the structure during the distributed discharge of the pulp prevents their dusting. The water delivered from the drainage means through a manifold 10 carries practically no suspended particles. The herein disclosed method of deposition does not require any additional operation of pre-forming a levee around the structure being deposited.

A structure formed by the herein disclosed method of deposition (a weir, a dam, etc.) a density 20 to 30 per cent higher than that of similar structures deposited according to hitherto known methods.

The method in accordance with the present invention provides for increasing the useful capacity of dumps and heaps, for increasing their height.

What we claim is:

1. A method of forming structures by deposition from a pulp, comprising the steps of laying drainage means at the base portion of the structure to be formed, said drainage means being associated with means for adjusting the rate of water outflow therefrom, depositing pulp directly on the ground above the drainage means so that water in the pulp outflows through the drainage means while solids in the pulp accumulate above the drainage means and form a deposited structure with upper inclined surfaces, and controlling the intensity of the outflow of water from said drainage means in the course of the depositing operation to progressively diminish outflow in the direction from the periphery of said structure beingdeposited toward the central portion thereof, said pulp, as it is being supplied, being distributed over the front of the formation of the inclined surfaces of said structure.

2. A method according to claim 1, wherein said pulp is distributed so that the solid particles of coarser fractions are deposited adjacent to said inclines of said structure and the solid particles of finer fractions are distributed adjacent to said central portion thereof. 

1. A method of forming structures by deposition from a pulp, comprising the steps of laying drainage means at the base portion of the structure to be formed, said drainage means being associated with means for adjusting the rate of water outflow therefrom, depositing pulp directly on the ground above the drainage means so that water in the pulp outflows through the drainage means while solids in the pulp accumulate above the drainage means and form a deposited structure with upper inclined surfaces, and controlling the intensity of the outflow of water from said drainage means in the course of the depositing operation to progressively diminish outflow in the direction from the periphery of said structure being deposited toward the central portion thereof, said pulp, as it is being supplied, being distributed over the front of the formation of the inclined surfaces of said structure.
 2. A method according to claim 1, wherein said pulp is distributed so that the solid particles of coarser fractions are deposited adjacent to said inclines of said structure and the solid particles of finer fractions are distributed adjacent to said central portion thereof. 